1. Technological Field
This technical disclosure pertains generally to electromechanical transducers and sensors, and more particularly to electromechanical transducers and sensors with enhanced frequency stability and tracking.
2. Background Discussion
Mechanical systems (and subsystems) typically have one or more resonant frequencies arising from various vibrational modes of the system. One important category of these mechanical systems are electromechanical transducers which convert mechanical motion into electrical signals in a sensing operation, and/or convert electrical signals into mechanical motion in an actuation operation. A transducer can therefore be used to sense the motion of a mechanical structure during actuation. It is often desirable to use the same transducer to actuate and sense the motion of the mechanical structure. However, there is often electrical feedthrough from the actuation signal to the sensor signal, which corrupts the sensor signal.
Electromechanical actuators may be configured to operate at or near resonance in order to increase the motion of the device, and mechanical sensors may also be operated at resonance to increase the sensitivity of the device. However, these electromechanical actuators and sensors suffer from variation in mechanical resonance that can arise due to fabrication tolerances and frequency drifting in response to changes in temperature, stress, humidity, or other ambient conditions.
In practice, electrical systems (and subsystems) are generally coupled to an electromechanical or electrical oscillator, and themselves may also vary in frequency due to fabrication tolerances, and be subject to frequency drift in response to changes in temperature, stress, humidity, or other ambient conditions. Therefore, in a system having an electrical subsystem and a mechanical subsystem, the resonance of the mechanical subsystem may drift independently of the operational frequency of the electrical subsystem.
Accordingly, a need exists for apparatus and methods which enables the resonance in an electromechanical system to be tracked by an electrical subsystem. The disclosure presented fulfills that need and provides additional benefits for resonant electromechanical systems.